Burst propagation in Texas Helimak

Autor(es)

Pereira, F. A. C. ; Toufen, D. L. ; Guimaraes-Filho, Z. O. ; Caldas, I. L. ; Gentle, K. W.

• Tipo de documento: Artigo Científico
• Fonte: Plasma Physics and Controlled Fusion; v. 58, n. 5, p. 8-pg., 2016-05-01.

Resumo

We present investigations of extreme events (bursts) propagating in the Texas Helimak, a toroidal plasma device in which the radial electric field can be changed by application of bias. In the experiments analyzed, a large grid of Langmuir probes measuring ion saturation current fluctuations is used to study the burst propagation and its dependence on the applied bias voltage. We confirm previous results reported on the turbulence intermittency in the Texas Helimak, extending them to a larger radial interval with a density ranging from a uniform decay to an almost uniform value. For our analysis, we introduce an improved procedure, based on a multiprobe bidimensional conditional averaging method, to assure precise determination of burst statistical properties and their spatial profiles. We verify that intermittent bursts have properties that vary in the radial direction. The number of bursts depends on the radial position and on the applied bias voltage. On the other hand, the burst characteristic time and size do not depend on the applied bias voltage. The bias voltage modifies the vertical and radial burst velocity profiles differently. The burst velocity is smaller than the turbulence phase velocity in almost all the analyzed region. (AU)

• Processo FAPESP: 11/19296-1 - Dinâmica não linear
• Beneficiário: Iberê Luiz Caldas
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 12/22108-5 - Controle da turbulência em plasmas
• Beneficiário: Dennis Lozano Toufen
• Modalidade de apoio: Bolsas no Exterior - Pesquisa
• Processo FAPESP: 14/07043-0 - Análise da turbulência e da propagação de estruturas em plasmas
• Beneficiário: Felipe Augusto Cardoso Pereira
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado